Prohibited Plant List

State & County Weed Laws 

Kirkland upholds Washington State’s noxious weed control law (Chapter 17.10 RWC), administered by the King County Noxious Weed Control Board. 'Noxious weeds' are non-native plants that, once established, are highly destructive, competitive and difficult to control. They have economic and ecological impacts and are very difficult to manage once they get established. Some are toxic or pose a threat to human and animal health, while others destroy native and beneficial plant communities. They are classified by the severity of their impact and appropriate control:  

  • Class A weeds must be eradicated or removed entirely throughout Washington State and King County
  • Class B and C weeds are to be controlled to prevent their spread in King County
Prohibited in Kirkland 

Of concern are a group of weeds listed by King County as ‘non-regulated’ and ‘weeds of concern’. Although they're not regulated by the state and county, these weed species impact and degrade native plant and animal habitat in open spaces and parks. To help attain the goals of the 20-Year Forest and Vegetation Restoration Plan, support the Urban Forest Management Plan, and support Green Kirkland Partnership efforts, the following weeds are prohibited to plant on private property in Kirkland, and are recommended for removal:

Evergreen/Himalayan blackberry  English/Atlantic ivy
English holly  Poison hemlock
Invasive knotweeds  Reed canarygrass
Bindweed or morning glory  Scotch broom
Bird cherry  Spurge laurel
Herb Robert  Yellow archangel


The removal of prohibited plant species (including significant trees) is allowed without a obtaining a permit except in sensitive areas such as wetland/stream buffers or landslide areas. Talk to a planner for more information about tree removal permits and sensitive areas.

The following plants that, while not prohibited, are discouraged to be planted on private property in Kirkland due to similar impacts to native forest areas:

 Butterfly bush
 European mountain ash
 English laurel
 Sycamore maple
 Common hawthorn
 Black locust